Exhaust pipe for internal combustion engines



Jan.Z5,1938 -O -HA SS'ON= 2,106,427

EXHAUST RIPE FOR NT ML. COMBUSTION ENGINES Filed March 12, 1936 Patented Jan. 25, 193

EXHAUST PIPE FOR INTERNAL COIVEUS- TION ENGHWES Oscar Hansson, Goteborg, Sweden Application March 12, 1936, Serial No. 68,554 In Sweden October 16; 1935 1 Claim.

This invention relatesto internal combustion engines, blowers or the like and particularly to the exhaust pipes of such engines. The main object of this invention is an exhaust pipe which 5 does not cause such resistance against the escape of the exhaust gases that the power of the engine becomes reduced. A further object of the invention is an exhaust pipe of such a character that an expansion of the exhaust gases occurs when flowing through said pipe, so that a vacuum is set forth therein which decreases the back pressure causing an increase of the net work done in the engine cylinder.

This invention is characterized mainly by the feature that the exhaust pipe is shaped as a difiuser. Experience, however, has shown that the diffuser shape should not be arbitrary but that it should follows. distinct rule in which the velocity and the pressure of the gas flow at the intake end of the exhaust pipe as well as the frequency of the exhaust impulses (the degree of discontinuity of the gas flow) are of considerable importance.

The rule of the shaping of the exhaust pipe two well known formulae of Euler, from which the following formula has been derived, viz:

i n L o L max x In this formula s is the variable cross section at the distance 2 inches from the smallest cross section so, in square inches while smax is the largest cross section and Lis the length in inches of the difluser measured between the cross sections 30 and Smax- The sections 30 and smflx are to be determined in each case according to the existing circum- 40 stances, that is, according to the gas volume passing through the pipe as well as to such velocities of the flow which are convenient with regard to the resistances in the pipe.

Experience has shown that a suitable relation between the various dimensions will be obtained if:

s,,=A.V.n, s,,,,,=B. 5,, and L='( -D. V.- :1 ns, In these formulae A, B, C and D are constants according to this invention is derived from the.

depending on the value of the piston speed, valve opening, number of cylinders and firing order p of the respective motor. V is the cylinder volume in cubic inches, 12 is the number of revolutions per minute, v is the maximum opening of the 5 exhaust valve in square inches and is the number of degrees for the crank shaft from the moment when the exhaust valve commences to lift until it has reached its full lift.

It is not necessary that the exhaust pipe in 10 its entire length has the configuration of a diffuser, but it can begin as well as end in a plain cylindrical tube according to the local circum-' stances. Further, this diffuser may be positioned more, close to or farther away from the exhaust 15 valves of the exhaust manifold in a multi-cylinder engine.

In the accompanying drawing an embodiment of this invention is illustrated by way of example, wherein 2 Figure 1 is"a sectional elevation view of the exhaust diffuser, and

Figures 2 and 3 cross-sections on the lines II II and III-III respectively of Figure 1.

In the drawing, designates the smallest cross-section, smax the largest cross section, and

L the total length of the diffuser, while the sections shown in Figures 2 and 3 can be designed as of the sizes s, and s: respectively, which are at the respective distances :c, and $2 off the smallest section 80- Having now particularly described and ascertained the nature of.,my said invention and in what manner the same is to be performed, I declare that what I claim is:-

A diffuser shaped-vacuum-producing exhaust pipe for internal combustion engines, blowers or the like characterized by the feature that the diffuser shape is determined by the following formula: 40 1 s, L a e x in which'formula s is the variable cross section at' the distance a: from the smallest cross section 5 so, while smaxi is. the largest cross section, and L is the length of the diffuser measured between the cross sections so and 8mm:-

OSCAR HANSSON. 6o 

